The BGS Lexicon of Named Rock Units — Result Details

South Stack Formation

Computer Code: NSS Preferred Map Code: notEntered
Status Code: Pending Upgrade
Age range: Ediacaran Period (AD) — Ediacaran Period (AD)
Lithological Description: Schistose greywackes with partings of mica-schist, or interbedded metasandstones, pelites and subordinate quartzites.
Definition of Lower Boundary: Unknown.
Definition of Upper Boundary: Drawn at conformable upward passage from grits of the Llwyn Beds to pelites, semi-pelites and metabasic rocks of the New Harbour Group.
Thickness: Approx. 360m to >1000m
Geographical Limits: Western parts of Holy Island and part on north-central Anglesey, north of the Carmel Head Thrust system.
Parent Unit: Holy Island Group (NHI)
Previous Name(s): South Stack Group (-2346)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  South Stack, Holy Island, Anglesey. 
Reference(s):
Shackleton, R M, 1954. The structure and succession of Anglesey and the Lleyn Peninsula. British Association for the Advancement of Science, Vol.11, p.106-108. 
Greenly, E. 1919. Geology of Anglesey. Memoir of the Geological Survey, UK. 
Blake, J F, 1888. The Monian System of rocks. Quarterly Journal of the Geological Society, Vol.44, p.476-480. 
Phillips, E, 1991. Progressive deformation of the South Stack and New Harbour Groups, Holy Island, Western Anglesey, North Wales. Quarterly Journal of the Geological Society, Vol.148, p.1091-1100. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable